Riding mower

ABSTRACT

A riding mower includes a pair of right and left propelling wheels, an engine disposed rearwardly of axles of the propelling wheels, a pair of right and left transmission cases corresponding to the propelling wheels and supporting the propelling wheels, respectively, a pair of right and left HSTs coupled to the transmission cases for outputting power thereto, respectively, a center case housing a power distributor for transmitting power from the engine to the pair of right and left HSTs, and a mower unit disposed forwardly of the propelling wheels. The center case is disposed forwardly of the axles of the propelling wheels.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to an improvement in a riding mower havinga mower unit disposed forwardly of propelling wheels.

[0003] 2. Description of the Related Art

[0004] A riding mower of this type is disclosed in U.S. Pat. No.4,809,796, for example. This known mower includes a pair of right andleft rear drive wheels (i.e. propelling wheels), a pair of right andleft driven dirigible front wheels, and a mower unit disposed betweenthe rear wheels and front wheels. Each of the right and left rear wheelshas an HST, and the front wheels are steered by a speed differencebetween the right and left rear wheels. The mower can make an in situturn by driving the right and left rear wheels in opposite directions.Thus, the mower has excellent small turn performance.

[0005] According to the prior art noted above, an engine is disposedsubstantially right over the rear wheels. A driver's seat is disposedbetween the front wheels and rear wheels and forwardly of the engine.This construction has an advantage of allowing main components of themower to be arranged en bloc between the front wheels and rear wheels.However, since the driver's seat is disposed forwardly of and relativelyfar from the rear wheels, the driver tends to be swung around when themower makes a very small turn such as an in situ turn. There is room forimprovement in this respect.

SUMMARY OF THE INVENTION

[0006] The object of this invention is to provide a riding mower whichovercomes the disadvantage noted above.

[0007] The above object is fulfilled, according to this invention, by ariding mower comprising a pair of right and left propelling wheels, andan engine for driving the propelling wheels. The engine is disposedrearwardly of axles of the propelling wheels. The mower furthercomprises a pair of right and left transmission cases corresponding tothe propelling wheels and supporting the propelling wheels,respectively, a pair of right and left HSTs coupled to the transmissioncases for outputting power thereto, respectively, and a center case fortransmitting power from the engine to the pair of right and left HSTs.The center case is disposed forwardly of the axles of the propellingwheels. A mower unit is disposed forwardly of the propelling wheels.

[0008] With the above construction, the mower according to thisinvention has the engine disposed in a further rearward position than inthe prior art, and the driver's seat may be disposed close to thepropelling wheels in the running direction. Consequently, the tendencyof the driver being swung around in time of a sharp turn such as an insitu turn is reduced since the driver may be seated close to the turningaxis.

[0009] Further, this riding mower has the center of gravity located nearthe propelling wheels to realize improved turning performance and spinturn performance.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a side elevation of a riding mower according to thisinvention;

[0011]FIG. 2 is a plan view showing the construction of the ridingmower;

[0012]FIG. 3 is a front view in vertical section of the riding mower;

[0013]FIG. 4 is a side view in vertical section of the rear half of themower showing a construction of a motor section;

[0014]FIG. 5 is a schematic cross section of the motor section showing atransmission structure;

[0015]FIG. 6(A) is a fragmentary front view showing a construction of ashift lever;

[0016]FIG. 6(B) is a fragmentary cross section showing the constructionof the shift lever;

[0017]FIG. 7(A) is a fragmentary front view showing a modifiedconstruction of the shift lever;

[0018]FIG. 7(B) is a fragmentary cross section showing the modifiedconstruction of the shift lever;

[0019]FIG. 8 is a fragmentary side view in vertical section showing aconstruction of a lift lever;

[0020]FIG. 9 is a hydraulic circuit diagram showing a construction ofhydrostatic stepless transmissions;

[0021]FIG. 10 is a side view in vertical section showing a constructionof a power distributor;

[0022]FIG. 11 is a rear view showing a connecting structure of a centercase, HST and transmission cases;

[0023]FIG. 12 is a side elevation of a front-mount type riding mower inanother embodiment;

[0024]FIG. 13 is a front view in vertical section showing a modifiedtransmission structure; and

[0025]FIG. 14 is a side view of a riding mower in a further embodimentof this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0026] An embodiment of this invention will be described hereinafterwith reference to the drawings.

[0027]FIG. 1 shows a side elevation of a riding mower.

[0028] This mower includes a body frame 1, a motor section 2 disposed ona rear portion of body frame 1, a driving platform 3 formed on a forwardportion of body frame 1, a pair of right and left propelling wheels 4arranged at rear portions of body frame 1. front wheels 5 acting asauxiliary wheels attached to right and left positions at forward ends ofbody frame 1 to be swivellable on vertical axes following movement ofthe mower, and a mower unit 7 suspended from the body frame 1 through alink mechanism 6 between propelling wheels 4 and front wheels 5. Thus,this riding mower is the mid-mount type.

[0029] Each of the right and left propelling wheels 4 is rotatablysupported through a corresponding axle 4 a.

[0030] As also shown in FIG. 2, the body frame 1 includes a pair ofright and left rear frames 8 extending longitudinally of the mower, witha predetermined transverse spacing therebetween, a U-shaped front frame9 interconnecting forward ends of the rear frames 8 and having oppositeends extending forward, a first connecting frame 10 interconnecting rearends of the rear frames 8, and a second connecting frame 11interconnecting forward ends of the front frame 9.

[0031] As shown in FIGS. 1 through 5, the motor section 2 includes awater-cooled diesel engine 12 with a lower portion thereof disposedbetween rear portions of the right and left rear frames 8, a center case13 housing a power distributor 13 a disposed forwardly of the lowerportion of engine 12, hydrostatic transmissions (HSTs) 14 acting asstepless change speed devices connected to opposite, right and left endsof power distributor 13 a, and transmission cases 15 housing reductiongears 15A connected to the right and left HSTs 14, respectively. Powertransmitted from the engine 12 through shafts is distributed right andleft by the power distributor 13 a. Each part of the power distributedis transmitted to the propelling wheel 4 through the HST 14 andreduction gears 15A. Thus, change speed operations may be performed forthe right and left propelling wheels 4 independently of each other.

[0032] Each transmission case 15 extends longitudinally of the mower.Each HST 14 is connected to the transmission case 15 in a positionforwardly of the axle 4 a.

[0033] The center case 13, right and left HSTs 14 and transmission cases15 are rigidly connected to one another. The center case 13 is disposedforwardly of the axles 4 a.

[0034] As shown in FIGS. 2 and 5, the right and left rear frames 8 arearranged-inwardly of the right and left transmission cases 15 and fixedthereto with bolts. That is, an entire transmission system including thepower distributor 13 a and right and left HSTs 14 and right and lefttransmission cases 15 has a rigid integral structure which reinforcesthe right and left rear frames 8 acting as right and left frame portionsof body frame 1 for supporting the mower unit 7 as suspended therefrom.As a result, a desirable frame structure is provided which has asufficient strength for supporting the mower unit 7 in suspension, whileachieving a simplified construction and lightening of the vehicle body.

[0035] As shown in FIGS. 1, 3 and 4, the driving platform 3 includesfootrests 16 arranged on the front frame 9, a driver's seat 17 disposedabove the center case 13, a pair of right and left shift levers 18arranged at opposite sides of driver's seat 17 to be rockable fore andaft, a lift lever 19 disposed outwardly of the right shift lever 18 tobe rockable fore and aft, a clutch lever 20 disposed rearwardly of theright shift lever 18 to be rockable fore and aft, and a parking brakelever 21 disposed below the left shift lever 18 to be rockable up anddown.

[0036] As shown in FIG. 2, the driver's seat 17 is disposed to overlapthe center case 13 in plan view.

[0037] As shown in FIGS. 3, 6 and 7, each of the right and left shiftlevers 18 includes a proximal linkage portion 18A interlocked to thecorresponding HST 14, and an operating portion 18B extending upward fromthe linkage portion 18A to be rockable right and left. The operatingportion 18B is movable as guided by a guide plate 22. The guide plate 22defines a T-shaped guide groove 22A including a shifting region h1 forallowing fore and aft rocking of the operating portion 18B, and aretracting region h2 for allowing the operating portion 18B to retractoutward from a neutral position in the shifting region h1 correspondingto the neutral state of HST 14. The right and left operating portions18B are curved so that extreme ends thereof are close to each other whenthe operating portions 18B are moved to corresponding positions in theshifting region h1.

[0038] With this construction, when the driver boards or alights fromthe mower, the operating portions 18B of the right and left shift levers18 may be moved from the neutral positions to the retracting regions h2to secure an open space forwardly of the driver's seat 17. This statealso provides an advantage of avoiding a misoperation of one or both ofthe shift levers 18 from the neutral position, which could occur whenpart of the driver's body inadvertently contacts the shift lever orlevers 18. When driving the mower, with each of the right and left shiftlevers 18 placed in the neutral position, the operating portion 18B maybe rocked forward or backward along the shifting region h1. Then, theright or left propelling wheel 4 may be driven with a driving torque andin a direction of rotation corresponding to an amount of operation ofthe right or left shift lever 18. Consequently, the mower may be drivenin various running states such as a straight forward or backward run, anordinary turn while running forward or backward, a pivot turn whilerunning forward or backward, and a spin turn. By holding the adjacentextreme ends of the right and left operating portions 18B in one hand,the driver may easily obtain a straight running state which requires theright and left shift levers 18 to be operated by the same amount.

[0039] As shown in FIGS. 6(A) and (B), the operating portion 18B mayemploy a square steel bar as a guided element 18 a guided by the guideplate 22, and include a grip 18 b in the form of a curved round steelpipe connected to the guided element 18 a through a connecting plate 18c. As shown in FIGS. 7(A) and (B), the operating portion 18B may employa round steel bar as the guided element 18 a, and include a grip 18 b inthe form of a curved round steel pipe fitted on the guided element 18 a.The latter has an advantage over the former in simplicity ofconstruction since the connecting plate 18 c is dispensed with. Inaddition, since the guided element 18 a and grip 18 b are coaxiallycoupled to each other, a positional adjustment to the neutral positionof each shift lever 18 may be made with ease. The latter constructionalso has an advantage of avoiding a twist of each shift lever 18 in timeof operation. Further, the round stick bar employed as the guidedelement 18 a allows each shift lever 18 to move smoothly from theshifting region h1 to the retracting region h2.

[0040] As shown in FIGS. 1, 2 and 8, the lift lever 19 has asmall-diameter gear 23 rotatable with rocking of the lever 19 about apivotal axis thereof and meshed with a large-diameter gear 24 of thelink mechanism 6. The link mechanism 6 has a parallelogram linkstructure including front links 6A connected for fore and aft pivotalmovement to right and left forward positions of the front frame 9 of thebody frame 1, a support shaft 6B extending between right and left rearpositions of and rotatably supported by the front frame 9, rear links 6Cconnected to opposite ends of the support shaft 6B to be pivotable withrotation of the support shaft 6B, and interlocking rods 6D foroperatively interconnecting the front links 6A and rear links 6C,respectively. The mower unit 7 is pivotally supported by free ends ofthe links 6A and 6C. The large-diameter gear 24 is mounted on thesupport shaft 6B to be rotatable therewith.

[0041] That is, the lift lever 19 is interlocked to the link mechanism 6through a servomechanism including the small-diameter gear 23 andlarge-diameter gear 24. The servomechanism allows the mower unit 7 to beraised and lowered with a relatively small operating force, while beingmaintained parallel to the body frame 1. To further reduce the operatingforce required for raising and lowering the mower unit 7, an assistingcylinder or spring may be mounted between the body frame 1 and linkmechanism 6 or mower unit 7.

[0042] The mower unit 7 is the three blade type having three rotaryblades rotatable about vertical axes and arranged sideways in itshousing. The mower unit 7 has a gearbox mounted on a center blade shaftfor receiving power from a power takeoff shaft 34 projecting from thecenter case 13.

[0043] As shown in FIG. 8, the lift lever 19 includes a control button26 biased by an internal spring 25 to project from an upper end of thelift lever 19. From the control button 26 extends a rod 27 having anengaging pin 27A provided at a lower end thereof. The pin 27A projectsright and left and is displaceable along the lift lever 19 adjacent theproximal end of the latter. When the control button 26 is pressed, theengaging pin 27A is movable under guidance of a guide groove 28A formedin a guide plate 28 erected on the front frame 9. The guide groove 28Ais shaped arcuate about the pivotal axis of the lift lever 19. When thecontrol button 26 is released, the engaging pin 27A is movable into oneof engaging grooves 28B extending radially of the guide groove 28A, andis maintained therein by the spring 25.

[0044] Thus, by pressing the control button 26, the lift lever 19 isoperable to raise or lower the mower unit 7 to a selected one of heightlevels. By releasing the control button 26, the mower unit 7 may belocked to the selected level.

[0045] As shown in FIGS. 5, 9 and 10, the clutch lever 20 is operable toswitch a two-position selector valve 33 mounted on a mower unit drivingoil line 32. This oil line 32 extends between a portion 29 a, at thedelivery side of a charge pump 30, of a charge oil line 29 extending tothe right and left HSTs 14, and a hydraulic clutch 31 for making andbreaking power transmission to the mower unit 7. The hydraulic clutch 31is included in the power distributor 13 a. When the selector valve 33 isswitched to an oil supply position, the clutch 31 is engaged by pressureoil supplied from the charge pump 30, against the biasing force of aclutch disengaging spring 31A. When the selector valve 33 is switched toan oil drain position, the clutch 31 is disengaged, with the pressureoil drained, by the biasing force of spring 31A. As a result, switchingis made between a state of transmitting power from the engine 12 to thepower takeoff shaft 34 included in the power distributor 13 a, and astate of breaking the power transmission to the power takeoff shaft 34.This switches the driving state of the mower unit 7 operativelyconnected to the power takeoff shaft 34 through a transmission shaftmechanism 35. The hydraulic clutch 31 includes a brake mechanism 36 forbraking the power takeoff shaft 34 when the clutch 31 is disengaged bythe biasing force of clutch disengaging spring 31A. Thus, the mower unit7 may be stopped operating as the power transmission to the powertakeoff shaft 34 is stopped. Reference B in FIG. 5 denotes brakemechanisms for braking the right and left propelling wheels 4 when theparking brake lever 21 is pulled up.

[0046] As shown in FIGS. 9 and 10, the portion 29 a, at the deliveryside of charge pump 30, of the charge oil line 29 includes a filter 37mounted thereon and a relief valve 38 connected to that portion 29 a.This construction can reduce the suction resistance of charge pump 30,compared with a case of installing the filter 37 on a portion 29 b ofcharge oil line 29 at the suction side of charge pump 30, therebysuppressing cavitation. This provides a proper charge pressure for theright and left HSTs 14, and a proper clutch pressure for the hydraulicclutch 31. Further, compared with a case of connecting relief valves 38to respective branch oil line portions 29c extending to the right andleft HSTs 14 from the portion 29 a of charge oil line 29 at the deliveryside of charge pump 30, the above construction requires only one reliefvalve 38, thereby achieving simplicity and low manufacturing cost.

[0047] Variable displacement pumps 53 of HSTs 14 and the charge pump 30are driven by the power from the engine 12. The portion 29 a of chargeoil line 29 at the delivery side of charge pump 30, the portion 29 b ofcharge oil line 29 at the suction side of charge pump 30, and the mowerunit driving oil line 32, are in the form of inner oil lines 13 c and 34a formed in the casing 13A of power distributor 13 a and in the powertakeoff shaft 34. This results in a simplified hydraulic pipingconstruction. Reference 39 in FIGS. 9 and 10 denotes strainers.Reference 13 b denotes a shaft for transmitting the power from theengine to the right and left HSTs. This shaft has, fixed thereto, abevel gear shown in a broken line.

[0048] As shown in FIG. 11, each HST 14 includes a casing of splitconstruction with an inner case 14a having the hydraulic pump 53 and ahydraulic motor 54, and an oil line block 14 b, which are coupled toeach other transversely of the mower. A pump shaft 53 a is mountedinside and splined to a hollow output shaft 13 b of the center case 13.The HSTs 14 are bolted directly to right and left walls of the centercase 13.

[0049] In the HST 14 disposed on the left side of center case 13, theoil line block 14 b corresponds to a “left case”, and the inner case 14a to a “right case”. In the HST 14 disposed on the right side of centercase 13, the inner case 14 a corresponds to the “left case”, and the oilline block 14 b to the “left case”.

[0050] As shown in FIG. 11, each transmission case 15 has a splitconstruction with an inner case portion 15 a and an outer case portion15 b. The transmission case 15 houses spur gear mechanisms 55 and 57arranged in two stages for transmitting power from a motor shaft 54 aacting as an output shaft of HST 14, at a reduced rate to the rear axle4 a. The two spur gear mechanisms 55 and 57 are interlocked through anintermediate shaft 59 having a portion thereof projecting from thetransmission case 15. This projecting shaft portion supports an internalexpanding brake B used chiefly as a parking brake. The transmissioncases 15 are bolted directly to side walls of HSTs 53 s a result, thefive components, i.e. transmission cases 15, HSTs 14 and center case 13are integrated to act also as a solid member for supporting the rightand left propelling wheels 4.

[0051] In the transmission case 15 disposed leftward from the centercase 13, the outer case portion 15 b corresponds to a “left case”, andthe inner case portion 15 a to a “right case”. In the transmission case15 disposed rightward from the center case 13, the inner case portion 16a corresponds to the “left case”, and the outer case portion 15 b to the“right case”.

[0052] As shown in FIG. 11, a plurality of bolts connecting each HST 14to the center case 13 include triad tightening bolts 60 extendingthrough the inner case 14 a, oil line block 14 b and center case 13. Aplurality of bolts connecting each pair of HST 14 and transmission case15 include tetrad tightening bolts 61 extending through the inner andoutside case portions 16 a and 15 b, inner case 14 a and oil line block14 b. All these bolts provide increased connecting strength.

[0053] As shown in FIGS. 1, 2 and 4, the motor section 2 includes,arranged in order from the driver's seat 17 toward the engine 12, a dustnet 40, a radiator 41, and a cooling fan 42 driven by the engine 12.These radiator 41 and cooling fan 42 constitute a radiator mechanism.The radiator mechanism is disposed, in plan view, between engine 12 andcenter case 13 and overlaps the axles 4 a of the propelling wheels 4 inthe fore and aft direction. The cooling fan 42 takes in ambient air fromadjacent the driver's seat 17 to cool cooling water flowing through theradiator 41, the engine 12, and other components. The ambient air takenin also prevents grass clippings, dust and the like scattered byoperation of the mower unit 7, from flowing toward the radiator 41.

[0054] As shown in FIGS. 2 through 4, a transmission shaft mechanism 43for transmitting power from the engine 12 to the power distributor 13 aincludes an air blowing fan 44 overlapping the right and left HSTs 14when seen in the fore and aft direction. The fan 44 is rotatable withthe transmission shaft mechanism 43 to take in ambient air from a regionbelow and rearwardly of the driver's seat 17, and direct the air towardthe right and left HSTs 14 arranged below the driver's seat 17. Thus,the right and left HSTs 14 are cooled efficiently. The ambient air aftercooling the intended components, and grass clippings, dust and the likescattered by operation of the mower unit 7, are restrained from flowingtoward the driver's seat 17, thereby providing improved workingenvironment for the driving platform 3. This construction alsoeffectively checks clogging of the dust net 40 for preventing thescattering grass clippings, dust and the like from flowing toward theradiator 41. The dust net 40 is box-shaped with vent portions 40A formedon the front, right and left and upper surfaces to provide an increasedsuction area.

[0055] As shown in FIG. 2, the motor section 2 accommodating the engine12 and its accessories such as the radiator 41 and cooling fan 42 iscontained in an outermost turning circle K of the propelling wheels 4.This feature greatly reduces the chance of the motor section 2contacting other objects when the mower makes a small turn such as aspin turn or a pivot turn by making a speed difference between the rightand left propelling wheels 4. Thus, the engine 12, radiator 41 andcooling fan 42 arranged in the motor section 2 are effectively protectedfrom damage. A small turn such as a spin turn or a pivot turn may beperformed near another object such as a wall, whereby a grass cuttingoperation may be carried out with increased facility.

[0056] Reference 45 in FIG. 1 denotes fuel tanks arranged laterally ofthe driver's seat 17 and acting also as fenders.

[0057] The right and left front wheels 5 are in the form of castersattached, to be swingable following movement of the mower. That is, thefront wheels 5 are steerable by the construction for turning the mowerby making a speed difference between the right and left HSTs 14. When anin situ turn is made by driving the right and left propelling wheels 4at the same speed in opposite directions, the right and left frontwheels 5 are turned 90 degrees sideways.

[0058] Other embodiments of this invention will be described brieflyhereinafter.

[0059] As shown in FIG. 12, the riding mower may be the front-mount typewith dirigible wheels 5 attached to right and left rear ends of bodyframe 1, and the mower unit 7 disposed forwardly of right and leftpropelling wheels 4.

[0060] The right and left HSTs 14 may be the belt type.

[0061] As shown in FIG. 13, where the right and left HSTs 14 are thehydrostatic type, each variable displacement pump 53 may be connected tothe power distributor 13 a, and each hydraulic motor 54 to thecorresponding propelling wheel 4. The corresponding variabledisplacement pump 53 and hydraulic motor 54 may be interconnectedthrough a hydraulic hose 14C.

[0062] Two air blowing fans 44 may be provided for the right and leftHSTs 14, respectively.

[0063]FIG. 14 shows a riding mower in a further embodiment of thisinvention. As shown in FIG. 14, a motor section 2 may have an engine 12disposed adjacent the axles of right and left propelling wheels 4, and acooling fan 42 and a radiator 41 arranged rearwardly of the engine 12.Thus, the center of gravity of the vehicle body is shifted forward tostabilize the weight balance of the vehicle body.

What is claimed is:
 1. A riding mower comprising: a pair of right andleft propelling wheels; an engine for driving said pair of right andleft propelling wheels, said engine being disposed rearwardly of axlesof said pair of right and left propelling wheels; a pair of right andleft transmission cases corresponding to said pair of right and leftpropelling wheels and supporting said propelling wheels, respectively; apair of right and left HSTs coupled to said pair of right and lefttransmission cases for outputting power to said transmission cases,respectively; a center case housing a power distributor for transmittingpower from said engine to said pair of right and left HSTs, said centercase being disposed forwardly of said axles; and a mower unit disposedforwardly of said propelling wheels.
 2. A riding mower as defined inclaim 1, wherein said engine is disposed in a position overlapping saidpair of right and left propelling wheels as seen from said axles.
 3. Ariding mower as defined in claim 1, further comprising a driver's seatdisposed in a position overlapping said center case in plan view.
 4. Ariding mower as defined in claim 1, further comprising a pair ofdirigible front wheels arranged forwardly of said mower unit.
 5. Ariding mower as defined in claim 1, wherein each of said transmissioncases extends longitudinally of said riding mower, said HSTs beingcoupled to said transmission cases in positions forwardly of said axles,respectively.
 6. A riding mower as defined in claim 1, furthercomprising a radiator mechanism disposed between said engine and saidcenter case in plan view, said radiator mechanism including a radiatorand a cooling fan.
 7. A riding mower as defined in claim 6, wherein saidradiator mechanism is disposed in a position overlapping said axleslongitudinally of said riding mower in plan view.
 8. A riding mower asdefined in claim 1, wherein said HSTs and said transmission cases aredirectly and rigidly interconnected, respectively.
 9. A riding mower asdefined in claim 8, wherein each of said pair of right and left HSTs isdirectly and rigidly connected to a side wall of said center case.
 10. Ariding mower as defined in claim 1, wherein each of said transmissioncases and said HSTs has a left case and a right case separable sideways,with bolts extending through a total of four left and right cases andinterconnecting each of said transmission cases and each of said HSTs,and bolts extending through the left and right cases of each of saidHSTs and said center case and interconnecting each of said HSTs and saidcenter case.
 11. A riding mower as defined in claim 6, wherein saidengine, said radiator and the said cooling fan are contained in anoutermost turning circle of said propelling wheels.
 12. A riding mowercomprising: a pair of right and left propelling wheels; an engine fordriving said pair of right and left propelling wheels, said engine beingdisposed rearwardly of axles of said pair of right and left propellingwheels, and in a position overlapping said pair of right and leftpropelling wheels as seen from said axles; a pair of right and lefttransmission cases corresponding to said pair of right and leftpropelling wheels and supporting said propelling wheels, respectively; apair of right and left HSTs coupled to said pair of right and lefttransmission cases for outputting power to said transmission cases,respectively; a center case housing a power distributor for transmittingpower from said engine to said pair of right and left HSTs, said centercase being disposed forwardly of said axles; and a mower unit disposedforwardly of said propelling wheels.